1. Field
Example embodiments of the following disclosure relate to a system, apparatus, and method for precisely estimating a three-dimensional (3D) position and a direction, and more particularly, to a system, apparatus, and method for selecting intensity information based on a sensitivity to noise and estimating a 3D position and a direction based on the selected intensity information, thereby enhancing the accuracy.
2. Description of the Related Art
In general, technology for estimating a three-dimensional (3D) position and a direction of a moving object or target may be used to sense a motion of an object, a human body, an animal, and the like, within a 3D space using expensive and large motion capturing equipment in the field of graphics or animation, and the like.
Consumer electronics (CE) motion sensing technology associated with the game industry has been gaining attention, and thus, many 3D position and direction methods using inexpensive and small motion capturing devices have been developed.
For example, a method of estimating a 3D position in a space may generally include a method of using a camera, a method of using an infrared ray, and a method of using an inertial sensor.
In the case of using a camera, it is possible to convert a position of a marker or light source, which is focused within a camera image, to a spatial 3D position, using a plurality of two-dimensional (2D) cameras. However, the accuracy of the conversion depends on a camera resolution, a marker size, and the like, and thus, it is difficult to perform highly accurate sensing.
In the case of using an ultrasonic wave, when the time of flight (TOF) of an ultrasonic wave from a transmitter to a receiver is measured, under the assumption that an ultrasonic wave moves at the velocity of sound, for example, about 340 m/s in the air, a distance may be calculated. When information about at least three same view distances is obtained, the 3D position may be calculated. In the case of using an ultrasonic wave, it is possible to perform highly precise sensing with inexpensive equipment, as compared to expensive equipment, such as, a camera. However, due to interference between sound waves, signals may not be simultaneously transmitted. Considering an ultrasonic signal attenuation time, for example, about 100 m/sec for 3 m, it may be difficult to estimate a position of a moving object in real time.
In the case of using an inertial sensor, it is possible to estimate a 3D position by integrating acceleration, motion and gravitational acceleration values, which are obtained using a gyro sensor, and a motion acceleration component that is calculated using angular velocity. However, errors may be accumulated over time. That is, the above method may perform a position estimation only within a short time interval, and thus, may not be suitable for the position estimation within a long time interval.
To solve the above issue, a method of estimating a 3D position and a direction using a signal attenuation characteristic of infrared ray is proposed. However, due to a nonlinearity of the signal attenuation characteristic, an area sensitive to noise may occur, which may affect the accuracy in estimating the 3D position and the direction.